The tech entrepreneur Robin Thurston bought roughly a dozen magazines, including the storied publication Outside, to create a digital hub for the outdoors. When he began scooping up titles, many of them were still profitable or breaking even, with committed but declining audiences. But Thurston seemed to have bigger ambitions than running a stable of small magazines that more or less broke even. In his initial meeting, he laid out a vision of “the Amazon Prime for the active-life-style participant,” with subscription numbers akin to those of Disney+ or Netflix. He estimated that the worldwide audience interested in healthy, active life styles was at least a billion people, and argued that the industry was recession-proof. But, from early on, writing was an uneasy fit with the business plan. “You cannot get a return on $150 million from niche media,” the former editor of Tips said. “The audiences they had weren’t sizable enough, and the structures they operated under were not scal...